When the first edition of this handbook was published, regulatory billing compliance for laboratory tests was not a major laboratory issue. Most hospital laboratories generally performed services for their own inpatients (and, occasionally, affiliated outpatients), and tests were billed according to a formula established by the business office. In the setting of prospective payment (e.g., diagnosis-related groups), payment credit was allocated based on a different formula. Today, however, microbiologists must be aware not only of the scientific basis of infectiousdisease diagnostics but also of the costing, coding, billing, and reimbursement for individual tests for patients seen in a broad spectrum of health care settings with coverage by an enormous number of health care plans. Jargon previously unknown in the clinical laboratory, such as reflex testing, upcoding, downcoding, local coverage decision (LCD), and national coverage decision (NCD), is now so extensive that a glossary of common terminology is included in this section (Appendix 1.1-1). The goal is to be reimbursed adequately for all appropriate work performed in a manner that is in compliance with all regulations.